1. Field of the Invention
This invention relates to a motor vehicle, such as an automobile, control system, and particularly, although not exclusively, to a motor vehicle control system provided with a plurality of control units.
2. Description of Related Art
It is known to use a microcomputer to control fuel supply or ignition timing for an automobile engine so as to improve fuel consumption and exhaust emissions. Microcomputer control of the operation or status of the automobile engine may be performed, as disclosed for instance in Japanese Patent Laid-Open No. 54-59529 (1979), through repeated calculation in an extremely short time based on the calculated results of the output data from a sensor.
Recently, however, the needs for enhanced quality of operation, improved drivability and comfort have become more important, requiring precise and sophisticated control of traction, automatic transmission gear shifts and/or suspension characteristics. As a result, there have been proposed several control means such as microcomputer controlled traction equipment, as disclosed in Japanese Patent Laid-Open No. 63-314332 (1988), microcomputer controlled changes (shifts) of automatic transmission gears as disclosed in Japanese Patent Laid-Open No. 63-57953 (1988), or microcomputer controlled suspension means as disclosed in Japanese Patent Laid-Open No. 61-295112 (1986).
On the other hand, there have been discussed and pursued new approaches toward a total control of an automobile by what is called a cooperative control including such control means as described above wherein they function not independently but in the best cooperative manner so that they may achieve an optimum performance under a given condition.
In the prior art, however, there has not been sufficient consideration to the particular configuration of control units relative to the total control performance of an automobile. In other words, the requirements for automobiles differ largely by type or model, some requiring better travel performance or fuel consumption, some requiring enhanced drivability or more comfort. Thus, control units to be mounted may differ largely according to specific requirements, and sometimes, they may be eliminated because of economy.
In order to provide an optimum total control for an automobile, the total control configuration in the automobile must be carefully considered according to the type of control units and the number of control units to be used. For this purpose, the detail or content of each control unit must be determined by carefully considering cooperative control assignments between each control unit. Therefore, when the need arises in the design of a make or model of automobile to change one control unit, it has been necessary to change the control functions of other, related, control units.
As a result, problems have arisen which have resulted in prolonged periods of time in developing control units, impairment in mass production and serviceability, and the like.
The object of the present invention is to provide a motor vehicle control whereby modification of a control unit is no longer required between different makes/models, further facilitating speedy development of control units, mass production, and serviceability in the market.